Display screen or portion thereof with a transitional graphical user interface



FIG. 1 is a front view of a display screen or portion thereof with a transitional graphical user interface showing a first image in a sequence of a first embodiment according to the claimed design;

FIG. 2 is a front view of a second image thereof;

FIG. 3 is front view of a third image thereof;

FIG. 4 is a front view of a fourth image thereof;

FIG. 5 is a front view of a display screen or portion thereof with a transitional graphical user interface showing a first image in a sequence of a second embodiment according to claimed design;

FIG. 6 is a front view of a second image thereof;

FIG. 7 is a front view of a third image thereof;

FIG. 8 is a front view of a display screen or portion thereof with a transitional graphical user interface showing a first image in a sequence of a third embodiment according to the claimed design;

FIG. 9 is a front view of a second image thereof;

FIG. 10 is a front view of a display screen or portion thereof with a transitional graphical user interface showing a first image in a sequence of a fourth embodiment according to the claimed design;

FIG. 11 is a front view of a second image thereof;

FIG. 12 is a front view of a third image thereof; and,

FIG. 13 is a front view of a fourth image thereof.

The appearance of the transition is sequential from FIG. 1 to FIG. 4 in the first embodiment, from FIG. 5 to FIG. 7 in the second embodiment, and from FIG. 8 to FIG. 11 in the third embodiment of the display screen supporting a transitional graphical user interface.

The process or period in which an image transitions to another image forms no part of the claimed design.

The shading in the figures indicate a contrast in appearance.

The dash-dot line shows the display screen or portion thereof and forms no part of the claimed design. The broken-line showing of numbers, text and graphic elements forms no part of the claimed design. 

CLAIM The ornamental design for a display screen or portion thereof with a transitional graphical user interface, as shown and described. 